Current wireless technology allows a user to be paged for an incoming call, and for the call to be routed to the user's wireless transmit/receive unit (WTRU), within the domain of a single wireless access network. However, support of paging and call routing between different access technologies (e.g., 2G/3G wireless networks, CDMA 2000 networks, WLAN/Bluetooth networks) is not provided for with current mechanisms. A mechanism is desired whereby “application level” paging and call routing is possible across heterogeneous access networks, allowing a WTRU to roam between these networks and seamlessly receive calls via the currently connected access network.